In a known rack bar of this design the spring clips are movably arranged in bores formed in the rack bar. In their clamping position, the spring clips are aligned substantially at right angles to the longitudinal direction of the rack bar. To load a plate to be coated and unload the coated plate, respectively, the known spring clips are lifted and swivelled aside. Since the spring clips formed as spring wire are rotatably supported in appropriate bores in the rack bar, there is the risk, due to the rotation of the spring clip during loading or unloading, of the coating of the rack bar becoming damaged in the area of the! bearing. Another drawback of the known arrangement is seen in the fact that, because of the alignment of the spring clip in the clamping position substantially perpendicular to the rack bar, the clamping clip protrudes with its clamping end relatively far into the plate to be coated so that the edge area of the plate which cannot be used is relatively large; in practice the width of the not usable plate edge is about 20 mm. Finally the swivelling of the spring clips according to the prior art is comparatively troublesome, because there is a relatively long moving distance of the spring clip and furthermore a rotation of about 90.degree. is necessary.
In another known embodiment of a rack bar each of the holding devices is in integrally formed holding block, and the holding blocks include recesses for inserting the plate to be coated, the plate being fixed by clamp bolts disposed in the holding blocks. It is considered to be a particular drawback in this arrangement that the plates cannot be loaded and unloaded frontally, i.e. in a direction perpendicular to the plate surface, without moving apart the rack bars supported at the work rail, which is time-consuming and inconvenient, however.